Microsoft RAS PPTP Clients disconnect random !

[massctrl]

hello,

We're having problems using a Mircrosoft RAS vpn pptp dial in.

The W2K server (with latest sp's & fixes) with RAS is a domain controller. has a fixed ADSL-ip and is behind a flowpoint router. The clients (xp and w2k with latest sp's) have a normal ADSL connection with a router capable to handle gre packets and dials in with the microsoft vpn client. Dialin and connecting is no problem. But the connection isn't stable! After 5,10,50 minutes, 1 hour 2 3 10 hours the connection drops. These times are very random.

- I've checked the MTU value made it 1372,1400,1472,1492 no results everythings stays the same
- flowpoint supports pptp (latest firmware)
- smc barricade at clientside supports pptp (latest firmware)
- all clients and server have latest fixes
- VPN clients are assigned a fixed LAN IP
- Clients log on to the domain using VPN (when pressing ctrl alt delete check box 'use dial in to log on domain'
- If a vpn connection is established over lan (as a test) it stays on for days without a problem

I'm out of inspiration here

Any ideas suggestions ?